Dual-band dual-polarized antenna array

Abstract

The present invention refers generally to a new family of antenna arrays that are able to operate simultaneously at two different frequency bands, while featuring dual-polarization at both bands. The design is suitable for applications where the two bands are centered at two frequencies f1 and f2 such that the ratio between the larger frequency (f2) to the smaller frequency (f1) is f2 / f1<1.5. The dual-band dual-polarization feature is achieved mainly by means of the physical position of the antenna elements within the array. Also, some particular antenna elements are newly disclosed to enhance the antenna performance.

Description

DESCRIPTIONOBJECT OF THE INVENTION[0001] The present invention refers generally to a new family of antenna arrays that are able to operate simultaneously at two different frequency bands, while featuring dual-polarization at both bands. The design is suitable for applications where the two bands are centered at two frequencies f1 and f2 such that the ratio between the larger frequency (f2) to the smaller frequency (f1) is f2 / f1<1.5. The dual-band dual-polarization feature is achieved mainly by means of the physical position of the antenna elements within the array. Also, some particular antenna elements are newly disclosed to enhance the antenna performance.[0002] The development of dual-band dual-polarization arrays is of most interest in for instance cellular telecommunication services. Both second generation (2G) cellular services, such as the European GSM900, GSM1800 and the American AMPS and PCS1900, and third generation (3G) cellular services (such as UMTS) take advantage o...

AI Technical Summary

Benefits of technology

[0001] The present invention refers generally to a new family of antenna arrays that are able to operate simultaneously at two different frequency bands, while featuring dual-polarization at both bands. The design is suitable for applications where the two bands are centered at two frequencies f1 and f2 such that the ratio between the larger frequency (f2) to the smaller frequency (f1) is f2 / f1<1.5. The dual-band dual-polarization feature is achieved mainly by means of the physical position of the antenna elements within the array. Also, some particular antenna elements are newly disclosed to enhance the antenna performance.

[0008] The antenna architecture consists on an interleaving of two independent vertically linear single-band arrays such that the relative position of the elements minimizes the coupling between antennas. Said spatial arranging of the antenna elements contributes to keeping the antenna size reduced to a minimum extent. In an scheme of the basic layout for the spatial arranging (interleaving) of the antenna, solid dots display the positions of the elements for the lower frequency f1, while the squares display the positions for the antenna elements for the upper frequency f2. Antenna elements for the higher frequency band f2 are aligned along a vertical axis with the desired spacing between elements. Said spacing is slightly smaller than a full-wavelength (typically below 98% the size of the shorter wavelength) for a maximum gain, although it can be readily seen that the spacing can be made shorter depending on the application.

[0010] Regarding the relative position of elements, elements for f2 are placed at certain positions along a vertical axis and horizontal axes such that the horizontal axes intersect both with the positions of said elements and the mid-point between elements at the neighbor axis; this ensures a maximum distance between elements and therefore a minimum coupling between elements of different bands.

Problems solved by technology

Keeping a minimum size for the antenna set-up in a BTS becomes a major issue when taking into account that the growth on the service demands forces operators in increasing the number of BTS, which is starting to produce a significant visual and environmental impact on urban and rural landscapes.

The problem becomes particularly significant when the operator has to provide both 2G and 3G services, because since both kinds of services operate at different frequency bands the deployment of both networks using conventional single-band antennas implies doubling the number of installed antennas and increasing the environmental impact of the installation.

The development of multiband antennas and antenna arrays is one of the main engineering challenges in the antenna field.

Due to this very simple principle, it is very difficult to make an array to operate simultaneously at two different frequencies or wavelengths, because is difficult to make the antenna element geometry to match in size two different wavelengths and similarly, it is difficult to find an spatial arranging of the antenna elements that meets the constraints of both wavelengths at the same time.

Said LPDA arrays where based on a non-uniform spacing of dipole elements of different sizes and were designed to cover a wide range of frequencies, however due their moderate gain (10 dBi) these designs have a restricted range of application and would not be suitable for applications such as for instance cellular services, where a higher gain (above 16 dBi) is required.

Also, neither the horizontal beamwidth (too narrow for BTS) nor the polarization and mechanical structure of said LPDA antennas match the requirements for BTS.

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